It's our only World Heritage site - and it was voted the most popular tourist destination in Northern Ireland last year.

But it seems that not everyone has been bewitched by the massive stretch of staircase-shaped rocks known as the Giant's Causeway.

Indeed, the site of the 40,000 or so interlocking hexagonal basalt columns recently got a resounding thumbs down in a snap survey of the world's must-see sights.

And when social media users were asked to name "the most overrated and underwhelming tourist attraction" they had ever visited, they gave the internationally famous landmark the "most negative mentions".

The stark criticism has been deftly batted away by Alastair Walker, site manager for the Giant's Causeway, which is run by the National Trust.

Describing it as "one of the most popular and iconic visitor attractions in the world, welcoming over 944,000 visitors from 184 countries" last year, Mr Walker said its success speaks for itself.

"The Giant's Causeway has consistently been graded as a five-star visitor attraction in the Tourism Northern Ireland Tourist Attraction grading scheme since the new Visitor Centre opened in July 2012," he said.

"It has also been named the UK's Best Heritage Attraction at the British Travel Awards for the past two years and is nominated again this year.

"These awards are the largest consumer poll in the UK and are awarded solely on public votes."

Referring to feedback, Mr Walker said the Giant's Causeway "consistently scores over 95% in terms of overall visitor satisfaction and enjoyment".

Alderman Norman Hillis, of the Causeway Coast & Glens Council, said he was "absolutely outraged" to hear the stinging negativity about "such a marvellous place".

"Can a million people be wrong? Because that's how many visitors we're expecting to come to the Giant's Causeway this year," he said.

"What I love about it is the fact that it's all-natural; you're getting the raw beauty of the Causeway Coast and some of the photos are magnificent.

"People come from all over the world to see it. Every time I myself go to visit it, I'm bowled over by its beauty."

He added: "It has so much to offer that we know people are leaving Dublin for day-trips just to see the Giant's Causeway."

His sentiments were shared by his Causeway Coast and Glens Council colleague Barney Fitzpatrick, who also extolled the landmark's virtues.

"It's been there for hundreds of years and people have been visiting it for hundreds of years; I can't see that changing," he commented.

"Everyone is entitled to their opinion but most people who visit are pleased that it's something they've seen at least once in their lifetime.

"There were over 900,000 visitors last year alone, which speaks volumes, and the majority go away satisfied with the experience."

Councillor Fitzpatrick added: "There's a lot more to the Giant's Causeway than looking at volcanic rocks - there's the exhibition centre, not to mention the mystery, magic and legend surrounding it."

The Irish Times said it had received "hundreds of responses" to its social media survey.

It said the Giant's Causeway topped the list of disappointing global attractions, followed by the Mona Lisa painting in the Louvre museum, Paris; the Manneken Pis statue in Brussels; the Little Mermaid sculpture in Copenhagen, and The Leaning Tower of Pisa in Italy.